RCU Forums

RCU Forums (https://www.rcuniverse.com/forum/)
-   Beginners (https://www.rcuniverse.com/forum/beginners-85/)
-   -   repair question (https://www.rcuniverse.com/forum/beginners-85/10461336-repair-question.html)

Minnreefer 04-13-2011 05:50 PM

repair question
 
1 Attachment(s)
I finally got around to repairing my stik, that lost it's wings in flight (they don't fly very well without wings)

I cut the fuselage off where it was bad and have built a new front half for it. I only have the 1/4 balsa sides and about 1 square inch of plywood holding the front half with the back half. It feels strong, but I don't fully trust it. I was thinking about putting some light fiberglass cloth on the sides to help reinforce it. I have a few questions.

1. is that a dumb idea to use some fiberglass to strengthen the bond.

2. would you use polyurethane or epoxy

3. I was going to use .75oz weight stuff (the really light stuff) is that enough?

4 would you do anything different or do you have any suggestions?

Thanks

Charlie P. 04-13-2011 06:02 PM

RE: repair question
 
Fiberglass cloth and epoxy is a good, strong repair but adds a lot of weight if you go overboard. It can alsobe a pain to sand flush. Plan ahead and laywaxed paper over the exterior epoxy for a smooth &finished cure. In a lot of repairs Ionly use epoxy at the stress points and use light balsa plyor popsicle sticks and Titebond II for the rest.

Minnreefer 04-13-2011 06:06 PM

RE: repair question
 
Thanks, the good thing that I have going for me is it is a stik, it is my beater plane, a fun plane to fly, but I don't care if it has a war wound or two and I think it can handle a little more weight ;)

I tend to fly planes better if I don't worry about crashing them )))))))))))))

Redback 04-13-2011 06:20 PM

RE: repair question
 
As reinforcement I would use a much heavier cloth than 0.75, especially if you can handle a little extra weight.

Just my $0.02

Terry

JRFisher 04-13-2011 06:52 PM

RE: repair question
 
I would just fishplate both sides with a lite ply doubler and cover it. You can see the doubler on a lot of profile planes.

jester_s1 04-13-2011 07:55 PM

RE: repair question
 
It looks like you have some overlap on both sides, so there should be enough material there. The only issue is that you're relying on the balsa on the outside for strength, so I'd put a 1 inch wide ply doubler on the inside so you have a continuous plywood structure. If you woodpecker it and use slow cure epoxy it'll be the strongest part of the whole airplane after that.

dredhea 04-14-2011 05:59 AM

RE: repair question
 
If you extend the ply doubler that's already there so that it goes the whole length of the wing saddle, it'll take another crash to make it come apart, but IMHO, it looks good the way it is.

JohnBuckner 04-14-2011 06:28 AM

RE: repair question
 
Ya, done pretty good! cover it and start flying it. Don,t make the mistake of getting into the mindset that you have reinforce to point that it will survive another single point landing without a wing.

Next time on a similar repair don't do a butt joint of the sides like that but rather a scarf joint, the sides cut and joined with an angle preferrably around forty five degress. When you use thicker sides on a box fuse like that you can if you like forego the ply full length doublers.

If you really want to do a bit more rather than fiberglas just epoxy 1/32 ply joint doublers on the inside of the butt joint on the balsa only not where the ply is and these little doublers only need to be about a half inch wide. Just stripes over the balsa butt joint.

John

Gray Beard 04-14-2011 10:26 AM

RE: repair question
 
1 Attachment(s)
Glassing to reinforce isn't all that good, as John pointed out, using some thin ply is much stronger. In the photos the first shot in my very old Kaos back in 04 after the fuel soaked wood let go. There was no outside wood left at all up front that wasn't oil soaked so I used some very thick balsa on the outside, it was I think 1/4 inch?? I didn't care about how it looked. At this point I had a YS 1.10 installed, I used a lot of different engines over the years in that plane. I used 1/32 ply on the inside as a doubler. Then last year I gave it the fourth covering job and was using an OS .91FS for power. Late last year I finally lost this old plane due to lack of altitude and an engine problem. The nose section of the plane didn't break off, well, it did but not in my repaired section anyway. After flying for about two decades it finally found it's expiration date.[&o]

armody 04-14-2011 12:09 PM

RE: repair question
 
Gray,

Are these planes designed by you? Are they scratch built or KiT, whatever they are, they are really nice and cool looking planes, I bet the fly in the air like a bat outta hell? They look pretty fast and sporty. Awesome planes. If you don't need another one you may send it to me lol :)

Mody

Minnreefer 04-14-2011 12:44 PM

RE: repair question
 
Thanks guys, I will add some plywood on the outside. I should have done a few things different, I made the new plywood on the inside, but I should have made it a little longs, I was not really thinking. I cut it there, mainly because that is about where it broke and I did not want to redo the servos (lazy) It is basically built the same as when I got it, I just want to add a little more. I am worried about the wooden mounts breaking off again (all 4 broke off with the wing, and the wing just floated down gently, while I was trying to use the elevator to bring the wingless body up from it's dive )) )


Mody, I believe most of the planes that Greybeard (Gene) has are Kaos, or more "vingtage" pattern planes 1 might be a birdie.

Gray Beard 04-14-2011 01:11 PM

RE: repair question
 
1 Attachment(s)


ORIGINAL: armody

Gray,

Are these planes designed by you? Are they scratch built or KiT, whatever they are, they are really nice and cool looking planes, I bet the fly in the air like a bat outta hell? They look pretty fast and sporty. Awesome planes. If you don't need another one you may send it to me lol :)

Mody
Mody, that is the same plane, just different covering. I told you the story of this plane in your other post. Here is the Dirty Birdy I replaced it with. First day of flight I got the DB in great trim, the next weekend I had my first mid air ever on it's first flight.
Both planes are a design by Joe Bridi and kit built. Both kits can be bough from Blue Jay and are very cheap kits. These are just old class C pattern planes. The DB really did fly better then the Kaos, just didn't last very long. The kits are old school and you get printed out instructions without any photos. They also don't tell you to cut a 6 inch piece from a 24 inch piece, they are designed for people that know how to build a kit the old way, you just need to think while building. These are what we call builders kits. They are both designed to use fixed gear or retracks. The Kaos at one point had retracks but I removed them and wint with fixed at some point. These are the perfect airplane designs, all the old pattern planes are great. You can read about them in the classic pattern forum. Take a little computer trip to the Blue Jay site. They are also sold through Bridi.
Gene

42etus 04-14-2011 02:49 PM

RE: repair question
 


ORIGINAL: Minnreefer

......................, while I was trying to use the elevator to bring the wingless body up from it's dive )) )


I've tried that too.........It doesn't work![:@]

SeamusG 04-14-2011 02:52 PM

RE: repair question
 
Minnreefer - the Bridi designs sold by Blue Jay are kits as they were sold "back in the day". Pictures? Who needs stinkin' pictures. Very satisfying build project. Check out the various build threads - a lot of good information.

Gray Beard 04-14-2011 03:10 PM

RE: repair question
 
I made templates of every part of the Yellow Birdy but just buying a new kit would be the easy way to go. For a taste over $100.00 you get everything and don't have to do all the thinking required to buy your wood. I would build another Dirty Birdy but I Have a couple pattern planes on hand so maybe in my future?? There are just so many nice planes, I hate to build the same plane twice. The Kazmirski Simla kit will be out sometime in June and it looks to be a great build too. There is a story and build article in Model Aviation March Magazine with all info.

Minnreefer 04-14-2011 04:46 PM

RE: repair question
 


ORIGINAL: SeamusG

Minnreefer - the Bridi designs sold by Blue Jay are kits as they were sold ''back in the day''. Pictures? Who needs stinkin' pictures. Very satisfying build project. Check out the various build threads - a lot of good information.


I know, I want to build one. I have yet to build a kit, since the last one that I built when I was 16 (a pt 20 I think?) I just need to get started, but I am just about done with my other repair projects and have started to clean my workshop area. I would love to build a 4*40 kit, but I just bought a built venture 60 with an engine and full remote for $140. Maybe I will build a smoothie or my hog bipe.


Gene, I saw that article about the Simla also, it looks very cool, I like those pattern planes, they do fly smooth.

rglgatortail 04-14-2011 04:59 PM

RE: repair question
 
this is what im wanting to get here in another month http://www.bridiairplanes.com/hangar/killerchaos60.html

Gray Beard 04-14-2011 05:50 PM

RE: repair question
 


ORIGINAL: rglgatortail

this is what I'm wanting to get here in another month http://www.bridiairplanes.com/hangar/killerchaos60.html
??? Mr. Bridi designed a lot of planes, the choice is up to you. They pretty much used the same design of wing. The Dirty Birdy has a different design fuse and does a much better knife edge. Last time I covered my Kaos I added to the fin area to get a better knife edge but then it would weather vane more in a cross wind. The DB just flew a bit smoother?? Maybe? My Kaos was also my high wind plane. Other then getting pushed back a little when going vertical wind had no effect on it at all. My Kaos was always with me, when I was having a bad day and couldn't get my thumbs to work the last thing I did was fly the Kaos so I left the field feeling good about myself. The Blue Jay kits are true to the original kits. I did notice some of the kits are now getting laser cut. That would be a good thing. Just don't expect the instructions to hold your hand through the build. These are not someones first build. Does it sound like I'm a big fan of the Bridi designs??:D

SeamusG 04-14-2011 05:53 PM

RE: repair question
 
Hey Robert - good choice. Here's my build thread for the Killer Chaos 60 (may it RIP) :( Too bad I sold my spare fuse pieces (sides, doublers & formers) before it did a belly flop.



John Sohm 04-14-2011 06:06 PM

RE: repair question
 

ORIGINAL: Minnreefer

Thanks guys, I will add some plywood on the outside. I should have done a few things different, I made the new plywood on the inside, but I should have made it a little longs, I was not really thinking. I cut it there, mainly because that is about where it broke and I did not want to redo the servos (lazy) It is basically built the same as when I got it, I just want to add a little more. I am worried about the wooden mounts breaking off again (all 4 broke off with the wing, and the wing just floated down gently, while I was trying to use the elevator to bring the wingless body up from it's dive )) )


Mody, I believe most of the planes that Greybeard (Gene) has are Kaos, or more ''vingtage'' pattern planes 1 might be a birdie.
Am I to understand that the wing just tore off the plane and floated down and that's what caused the crash and resulting damage? Because if that's the case, I think I would be more concerned with the method you used to attach the mounting blocks to start with. Those blocks should always be epoxied in place. Don't use CA because it has one of the weakest bonds of any adhesive in the shear direction. Wood working glue aka Aliphatic glue is strong but make sure there's a good fillet around the joint but I always use epoxy.

Your repair looks like it should be strong enough as is but I also agree with the thin plywood or even carbon fiber tape to reinforce the joint. We used to take a piece of 1/4" ply about 1/2" wide x 3" long and glue a little handle to it. Then on the bottom opposite the handle, glue a strip of 60 or 80 grit sandpaper about 1/4" to 3/8" wide by the length of the base plus a little overlap to secure the sandpaper. Now, using a straight edge, run the little block along the straight edge to sand an indent in the balsa side until the base of the sander contacts the outer surface of the sheeting. You'll have an indent that is just the thickness of the sandpaper and at 60 to 80 grit, should be somewhere around 1/32" if I'm not too far off. Mix up some 15 Minute epoxy and glue your plywood strengthener in the groove and you should be all set. Wipe off any excess with a little alcohol on a paper towel before the epoxy totally sets.

Hope this helps you out a bit.

Gray Beard 04-14-2011 06:11 PM

RE: repair question
 


ORIGINAL: John Sohm


ORIGINAL: Minnreefer

Thanks guys, I will add some plywood on the outside. I should have done a few things different, I made the new plywood on the inside, but I should have made it a little longs, I was not really thinking. I cut it there, mainly because that is about where it broke and I did not want to redo the servos (lazy) It is basically built the same as when I got it, I just want to add a little more. I am worried about the wooden mounts breaking off again (all 4 broke off with the wing, and the wing just floated down gently, while I was trying to use the elevator to bring the wingless body up from it's dive )) )


Mody, I believe most of the planes that Greybeard (Gene) has are Kaos, or more ''vingtage'' pattern planes 1 might be a birdie.
Am I to understand that the wing just tore off the plane and floated down and that's what caused the crash and resulting damage? Because if that's the case, I think I would be more concerned with the method you used to attach the mounting blocks to start with. Those blocks should always be epoxied in place. Don't use CA because it has one of the weakest bonds of any adhesive in the shear direction. Wood working glue aka Aliphatic glue is strong but make sure there's a good fillet around the joint but I always use epoxy.

Your repair looks like it should be strong enough as is but I also agree with the thin plywood or even carbon fiber tape to reinforce the joint. We used to take a piece of 1/4'' ply about 1/2'' wide x 3'' long and glue a little handle to it. Then on the bottom opposite the handle, glue a strip of 60 or 80 grit sandpaper about 1/4'' to 3/8'' wide by the length of the base plus a little overlap to secure the sandpaper. Now, using a straight edge, run the little block along the straight edge to sand an indent in the balsa side until the base of the sander contacts the outer surface of the sheeting. You'll have an indent that is just the thickness of the sandpaper and at 60 to 80 grit, should be somewhere around 1/32'' if I'm not too far off. Mix up some 15 Minute epoxy and glue your plywood strengthener in the groove and you should be all set. Wipe off any excess with a little alcohol on a paper towel before the epoxy totally sets.

Hope this helps you out a bit.
ARF, he had never built a kit before. That makes the repair job even more impressive. I'm pretty sure using any glue at all is a big improovment. Doing a repair like this is also a great learning tool.

Minnreefer 04-14-2011 07:17 PM

RE: repair question
 
I got the plane mostly built as a kit build, (someone else built it) I did not install the mounting blocks, but that still worries me. When I installed new ones I epoxied them well, but I still worry about that for strength.

I am going to use 1/32 ply to help make the joint a bit stronger.

Thanks guys, I really am not that worried about building planes, I just need to get some extra time and confidence.

JohnBuckner 04-14-2011 07:30 PM

RE: repair question
 
1 Attachment(s)
A couple more Kaos'

Mine is a Killer from the original kit and it also serves a the 'Sea Kaos'

John

SeamusG 04-14-2011 07:37 PM

RE: repair question
 
It looks like the fuse wing mounts are made of 1/4" plywood with 1/4x20 holes tapped. I can't tell if there is an tri-stock glued to the bottom side of the mounts and the fuse. If NOT - add 3/4" (at least 1/2") tri-stock. It should help to connect the mounts to both the fuse sides AND the former at the rear of the wing bay. Then just drill undersized holes thru the existing mounting holes and tap them to match the original. Use 30-min epoxy for the glue.

Minnreefer 04-14-2011 07:55 PM

RE: repair question
 


ORIGINAL: SeamusG

It looks like the fuse wing mounts are made of 1/4'' plywood with 1/4x20 holes tapped. I can't tell if there is an tri-stock glued to the bottom side of the mounts and the fuse. If NOT - add 3/4'' (at least 1/2'') tri-stock. It should help to connect the mounts to both the fuse sides AND the former at the rear of the wing bay. Then just drill undersized holes thru the existing mounting holes and tap them to match the original. Use 30-min epoxy for the glue.

I did that, thanks, I think the original builder used ca glue for that part. I should not have trusted him, he built the horizontal stab is off by 3/4" vertical compared to the wing.


All times are GMT -8. The time now is 10:13 PM.


Copyright © 2026 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.